View Full Version : Permanent Magnets To Bulk Erase Tapes?


DaveThreshol
07-18-2007, 01:00 AM
I read somewhere that you can use magnets to bulk erase tapes. These would be 10.5" N.A.B. tapes that I have. I have some big 4" bucking magnets that I was going to try. So my question is, will this hurt anything? I don't want to find out that I wrecked them.

I just held a wrench up to my Radio Shack bulk eraser, and it acted just like an electro-magnet. The shack unit just isn't quite enough power to really get them. When used on both sides, it gets about 1/2 of the audio off.

Any suggestions?

ferninando
07-18-2007, 01:22 AM
try to get a nortronics QM211 bulk eraser. It's a serious tape eraser and will suck the magnetic field out of any tape that comes near it. It's a serious electromagnetic bulk eraser.

markthefixer
07-18-2007, 02:25 AM
Yup, I tried to use a color tv de-gaussing coil to erase some vhs tapes... no dice.... the tape played just fine afterwards...

I suspect I tried some magnets first, with similarly disappointing results.

I suspect the alternating magnetic field is better for erasing than a static magnetic field.

Fred Longworth
07-18-2007, 02:57 AM
I use a bulk eraser. It works wonderfully.

I also use it to demagnetize tools for when I'm working on tape decks.

Fred Longworth

Maron Horonzakz
07-18-2007, 08:59 AM
The trick is to SLOWLEY pull the demagnatiser away from the tape and the field getting weaker and weaker...Just Placeing a magnet next to a tape will only magnetize a large blotch making things worse.

Web Police
07-18-2007, 09:52 AM
With most bulk erasers you need to run it on both sides of the reel to reel tape as the magnetic field falls off rapidly with the distance from the bulk eraser. Most permanent magnets do not have enough of a field to properly erase tapes.

DaveThreshol
07-19-2007, 11:00 PM
Hey thanks a lot everyone. I think I'll just but a new bulk eraser.:music:

Arkay
07-20-2007, 12:15 AM
I have a cassette tape eraser that is made with good-sized permanent magnets, set at (right?) angles (and I believe reversed polarities, although it has been years since I checked that) to each other. They are affixed in a case, with a slot in between them, through which you push the cassette. For a complete and total erasure, I put the tape through once, then turn it around and put it through the other direction. I don't know if the second pass is necessary, but I do it just for insurance. Never fails to completely erase the tape. I imagine something similar on a larger scale would work well enough for bulkier tapes. In fact, just waving this cassette eraser over a reel of tape, for the whole side on both sides, does the job nicely.

A magnetic field is a magnietic field, regardless of how it is generated. Only if you are rapidly switching polarity (changing magnetic force lines direction) would the means of generating the magnetic field be important. I think electical demagnetizers do this, and it is presumably the fastest and most effective/efficient way, but it isn't 100% necessary. You CAN erase tape with permanent magnets, if you get the directions and motions correct. Anyone who doubts this can play with my cassette eraser and learn the truth of it.

DaveThreshol
07-20-2007, 01:58 AM
I have a cassette tape eraser that is made with good-sized permanent magnets, set at (right?) angles (and I believe reversed polarities, although it has been years since I checked that) to each other. They are affixed in a case, with a slot in between them, through which you push the cassette. For a complete and total erasure, I put the tape through once, then turn it around and put it through the other direction. I don't know if the second pass is necessary, but I do it just for insurance. Never fails to completely erase the tape. I imagine something similar on a larger scale would work well enough for bulkier tapes. In fact, just waving this cassette eraser over a reel of tape, for the whole side on both sides, does the job nicely.

A magnetic field is a magnietic field, regardless of how it is generated. Only if you are rapidly switching polarity (changing magnetic force lines direction) would the means of generating the magnetic field be important. I think electical demagnetizers do this, and it is presumably the fastest and most effective/efficient way, but it isn't 100% necessary. You CAN erase tape with permanent magnets, if you get the directions and motions correct. Anyone who doubts this can play with my cassette eraser and learn the truth of it.Thanks Arkay. THAT'S what I'm talking about! LOL I'm going to try some big bucking magnets. I'll make a he-man version of yours. I just wanted to make sure it wouldn't wreck the tapes. LOL

Web Police
07-20-2007, 07:37 AM
I also have a cassette tape eraser with permanant magnets and you slide the cassette through slowly one pass on either side. It erases the tape however it leave a higher level of background noise than does the electro magnet bulk eraser I have. The permananet magnet will leave -30db peaks on the tape while the electro magnet eraser's peak are -70db. It might not make a big difference when re-recording them though. :scratch2:

I don't know about making an eraser as the magnets polarity may not be correct in relation to the tapes and may do just as much harm as good. They sell the permananet magnet cassette erasers on-line for a a Hamilton and a few Washingtons though.

dragon
01-05-2008, 01:11 PM
Back in the 70's I owned a VW van that I decided to add speakers to. I mounted two small speakers in the glove box lid...hey it was an easy install. And yep, the cassettes stored inside were erased by the magnets on the speakers. I've also used rare earth mags to erase VHS tapes too. gil